html {
height: 100%;
}
body {
height: 100%;
background: #222;
display: flex;
align-items: center;
justify-content: center;
}
canvas {
border-radius: 6px;
box-shadow: #000 2px 2px 24px;
background:
repeating-linear-gradient(to right, #000, #000 8px, #fff 8px, #fff 16px),
repeating-linear-gradient(#666, #666 8px, #999 8px, #999 16px);
background-blend-mode: exclusion;
}